The invention generally relates to a valve within a downhole control line. More specifically, the invention relates to a valve within a downhole control line, which valve is adapted to prevent blow-outs through the control line while simultaneously allowing bi-directional flow or pressure transfer through the control line.
A hydraulic control line is typically used in subterranean wellbores to control a downhole tool. Increases of pressure, decreases of pressure, and/or pressure fluctuations within the control line direct the tool to perform certain functions. For instance, an increase in pressure can move a sleeve valve from a first, open position to a second, closed position. In turn, a subsequent decrease in pressure can enable the movement of the sleeve valve back to its first, open position. Hydraulic control lines can also be used to control other types of valves (such as ball valves, disc valves, etc.), packers, and perforating guns, among others.
Since hydraulic control lines extend from downhole to the surface, they provide a flow path independent of the production tubing or wellbore. If a blow-out occurs in the wellbore, sealing the blow-out within the wellbore and production tubing may still allow the blow-out to pass through the control line, since the control line is an independent flow path. Therefore, to truly control blow-outs in wellbores with hydraulic control lines, a mechanism must be in place to seal off the control line as well as the wellbore/production tubing in case of a blow-out.
Typically, a one-way check valve, such as a spring-ball arrangement, is included in the control line. The check valve enables flow in the downhole direction, but does not allow flow in the uphole direction thereby preventing blow-outs. However, depending on the control line and downhole tool system, it may be necessary to enable flow in both directions within the control line while simultaneously preventing blow-outs through the control line.
Thus, there is a continuing need to address one or more of the problems stated above.